The present invention is generally directed to combinations of antiviral compounds, and more specifically directed to combination pharmaceutical agents, which can inhibit the function of the NS5A protein encoded by Hepatitis C virus (HCV) and the NS3 protease encoded by HCV.
HCV is a major human pathogen, infecting an estimated 170 million persons worldwide-roughly five times the number infected by human immunodeficiency virus type 1. A substantial fraction of these HCV infected individuals develop serious progressive liver disease, including cirrhosis and hepatocellular carcinoma. (Lauer, G. M.; Walker, B. D. N. Eng. J. Med. (2001), 345, 41-52).
Presently, the most effective HCV therapy employs a combination of pegylated alpha-interferon and ribavirin, leading to sustained efficacy in 50% of patients and a treatment that is superior to unmodified alpha-interferon as monotherapy (Zeuzem, S. et al. N. Engl. J. Med. (2000), 343, 1666-1672). However, even with experimental therapeutic regimens involving combinations of pegylated alpha-interferon and ribavirin, a substantial fraction of patients do not have a sustained reduction in viral load. Thus, there is a clear and unmet need for effective therapeutics for the treatment of HCV infection.
HCV is a positive-sense single stranded RNA virus. Based on a comparison of the deduced amino acid sequence and the extensive similarity in the 5′ untranslated region, HCV has been classified as a separate genus in the Flaviviridae family. All members of the Flaviviridae family have enveloped virions that contain a positive-sense single stranded RNA genome encoding all known virus-specific proteins via translation of a single, uninterrupted, open reading frame.
Considerable heterogeneity is found within the nucleotide and encoded amino acid sequence throughout the HCV genome. At least six major genotypes have been characterized, and more than 50 subtypes have been described. The major genotypes of HCV differ in their distribution worldwide, and the clinical significance of the genetic heterogeneity of HCV remains elusive despite numerous studies of the possible effect of genotypes on pathogenesis and therapy.
The positive-sense single strand HCV RNA genome is approximately 9500 nucleotides in length and has a single open reading frame (ORF) encoding a single large polyprotein of about 3000 amino acids. In infected cells, this polyprotein is cleaved at multiple sites by cellular and viral proteases to produce the structural and non-structural (NS) proteins. In the case of HCV, the generation of mature non-structural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) is effected by two viral proteases. The first one is believed to be a metalloprotease and cleaves at the NS2-NS3 junction; the second one is a serine protease contained within the N-terminal region of NS3 (also referred to herein as NS3 protease) and mediates all the subsequent cleavages downstream of NS3, both in cis, at the NS3-NS4A cleavage site, and in trans, for the remaining NS4A-NS4B, NS4B-NS5A, NS5A-NS5B sites. The NS4A protein appears to serve multiple functions, acting as a cofactor for the NS3 protease and assisting in the membrane localization of NS3 and other viral replicase components.
The complex formation of the NS3 protein with NS4A seems necessary to the processing events, enhancing the proteolytic efficiency at all of the sites. The NS3 protein also exhibits nucleoside triphosphatase and RNA helicase activities. NS5B is an RNA-dependent RNA polymerase that is involved in the replication of HCV.
Among the compounds that have demonstrated efficacy in inhibiting HCV replication, as selective HCV serine protease inhibitors, are the peptide compounds disclosed in Patent No. WO/1999/007733, WO/2005/007681, WO/2005/028502, WO/2005/035525, WO/2005/037860, WO/2005/077969, WO/2006/039488, WO/2007/022459, WO/2008/106058, WO 2008/106139, WO/2000/009558, WO/2000/009543, WO/1999/064442, WO/1999/007733, WO/1999/07734, WO/1999/050230 and WO/1998/017679. NS5B polymerase inhibitors have also demonstrated activity. These agents include but are not limited to other inhibitors of HCV RNA dependent RNA polymerase such as, for example, nucleoside type polymerase inhibitors described in WO01/90121(A2), or U.S. Pat. No. 6,348,587B1 or WO01/60315 or WO01/32153 or non-nucleoside inhibitors such as, benzimidazole polymerase inhibitors described in EP 162196A1 or WO02/04425. However, none of these compounds have, to date, progressed beyond clinical trials (De Clercq, E. J. Clin. Virol. 2001 22 73-89).
In addition to the combinations of pegylated alpha-interferon and ribavirin, other combinations of compounds useful for treating HCV-infected patients are desired which selectively inhibit HCV viral replication. In particular, pharmaceutical agents which are effective to inhibit the function of the NS5A protein in combination with those effective to inhibit other viral targets are desired. The HCV NS5A protein is described, for example, in Tan, S.-L.; Katzel, M. G. Virology (2001) 284, 1-12, and in Park, K.-J.; Choi, S.-H, J. Biological Chemistry (2003). The relevant patent disclosures describing the synthesis of HCV NS5A inhibitors are: US 2009/0202478; US 2009/0202483; WO 2009/020828; WO 2009/020825; WO 2009/102318; WO 2009/102325; WO 2009/102694; WO 2008/144380; WO 2008/021927; WO 2008/021928; WO 2008/021936; WO 2006/133326; WO 2004/014852; WO 2008/070447; WO 2009/034390; WO 2006/079833; WO 2007/031791; WO 2007/070556; WO 2007/070600; WO 2008/064218; WO 2008/154601; WO 2007/082554; WO 2008/048589; WO 2010/017401; WO 2010/065668; WO 2010/065674; WO 2010/065681, the contents of each of which are expressly incorporated by reference herein.